1. Field of Invention
This invention relates to a method and apparatus for treatment of water and, in particular, to an improved method and apparatus for treatment of water with an electrolytic cell having a sacrificial magnesium anode.
1. Brief Statement of the Prior Art
The chemical treatment of water which contains calcium and magnesium carbonates and bicarbonates, commonly referred as hardness, is widely practiced to reduce scaling and corrosion of the water handling equipment. While it has been known for some time that water can be treated by passing the water over an electrolytic cell formed of a sacrificial magnesium anode and a copper cathode, the treatment has been met with limited success. U.S. Pat. No. 3,342,712, discloses an early attempt to develop an efficient method and apparatus for this treatment. In my prior U.S. Pat. No. 5,094,739, I have disclosed an improved method and apparatus for treatment of water with a magnesium and copper electrolytic cell having electrode assemblies of magnesium and copper plates separated by thin spacers, in an attempt to provide extended electrode surfaces which would resist polarization. In such apparatus, the electrolytic cell has been suspended or mounted within a mild or stainless steel treatment vessel.
The treatment of water with magnesium invariably has resulted in the formation of soft, flocculent precipitates of calcium. These precipitates are non-adhesive and typically have accumulated within the vessel housing the electrolytic cell, requiring frequent, usually monthly, cleaning and backflushing with water to remove the precipitates. During the monthly servicing, the electrode assembly has also been replaced to clean polarizing coatings from the electrode surfaces.
As disclosed in my aforementioned patent, the electrolytic cell is formed of alternating magnesium and copper plates which are assembled by a fastener such as a brass bolt which is passed through aligned holes in the plates, using brass washers interspaced between the plates to maintain the plates in a spaced apart parallel array. During the monthly cleaning and repair of the electrolytic cells assembled in this fashion, many of the magnesium anodes required replacement because of abnormal enlargement of the holes in the plates. This prevented efficient utilization of the sacrificial magnesium anodes. Further, the magnesium consumption in these electrolytic cells was quite substantial; a typical single household installation consuming about one pound of magnesium per month.